This invention relates to medical devices for use in a body lumen.
A venous valve functions to prevent retrograde flow of blood and allow only antegrade flow of blood to the heart. Referring to FIG. 1A, a healthy venous valve 12 is illustrated in a vessel 10. The valve is bicuspid, with opposed cusps 14. In the closed condition, the cusps 14 are drawn together to prevent retrograde flow (arrow 16) of blood. Referring to FIG. 1B, if the valve is incompetent, the cusps 14 do not seal properly and retrograde flow of blood occurs. Incompetence of a venous valve is thought to arise from at least the following two medical conditions: varicose veins and chronic venous insufficiency.
This invention relates to medical devices for use with a body lumen. In one aspect, the invention features a medical device including a membrane implantable in a body lumen and invertably deformable between a first position and a second position. The membrane is invertible in response to the direction of fluid flow through the lumen and can be deformable by fluid flow in the body lumen. The membrane can be invertable relative to a radial direction of the body lumen. The membrane can be reversibly deformable between the first position and the second position.
Implementations can include one or more of the following. The membrane can define a portion of a cone, and can include an anchoring element adjacent a vertex of the cone. The membrane can include an anchoring element configured to embed within the body lumen, or alternatively configured to penetrate through the body lumen. The anchoring element may be, for example, a loop or a barb. The membrane can be formed of a polymer, for example, a polyurethane, polyethylene or fluoroplastic.
In another aspect, the invention features a medical system. The system includes multiple membranes, each membrane implantable in a body lumen and invertably deformable between a first position and a second position. Each membrane is invertible in response to the direction of fluid flow through the lumen.
Implementations of the system can include one or more of the following. The membranes can be symmetrically implantable in the body lumen. Each membrane can be invertable relative to a radial direction of the body lumen and can be deformable by fluid flow in the body lumen. At least one membrane can be reversibly deformable between the first position and the second position. At least one membrane can define a portion of a cone and can include an anchoring element adjacent a vertex of the cone. At least one membrane can include an anchoring element configured to embed within the body lumen or alternatively configured to penetrate through the body lumen. The anchoring element can be, for example, a loop or a barb. At least one membrane can be formed of a polymer, for example, a polyurethane, polyethylene or fluoroplastic.
In another aspect, the invention features a method. The method includes positioning at least one membrane in a body lumen, each membrane invertably deformable between a first position and a second position. Each membrane is invertible in response to the direction of fluid flow through the lumen.
Implementations of the method can include one or more of the following. The method can include positioning multiple membranes in the body lumen. The multiple membranes can be positioned symmetrically in the body lumen. The method can include penetrating an anchoring element of the at least one membrane through the body lumen or, alternatively, embedding an anchoring element of the at least one membrane into the body lumen.
In another aspect, the invention features a method of controlling flow in a body lumen. The method includes invertably deforming a membrane between a first position and a second position, the membrane being invertible in response to the direction of fluid flow through the lumen. Implementations can include one or more of the following. The membrane in the second position and a portion of the body lumen can define a cavity. Deformation of the membrane can be relative to a radial axis of the body lumen. The membrane can be deformable by fluid flow in the body lumen. The membrane in the first position and the membrane in the second position can be approximately mirror images of each other. The method can further include invertably deforming a plurality of membranes.
Embodiments may have one or more of the following advantages. One or more invertible membranes, which can function as artificial valve cusps, can be implanted at a treatment site using a catheter. As such, implantation is minimally invasive and avoids surgery and the possibility of the inherent complications. The membrane is fabricated from a polymer such as a polyurethane, polyethylene or fluoroplastic, which materials are more easily accessible than a natural tissue excised from an animal, and can be manufactured with consistency and efficiency that could be more difficult or more expensive using a natural tissue.
Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.